The rapidly spreading chaos in Libya should give the American people pause, and may end up giving the U.S. military another item to add to its endless to-do list. Setting the stage for what might be called the battle for Tripoli, anti-government forces and rebel military units are moving from the country’s apparently “liberated” east to face off against Moammar Gadhafi’s Praetorian Guard of tribal and regime loyalists. The New York Times described clusters of heavily armed men in mismatched uniforms clutching machine guns,” “dozens of checkpoints operated by . . . plainclothes militiamen,” and “machine-gun toting foreign mercenaries” stalking the capital, and compared the unfolding situation to the anarchy in Somalia.

The emerging Libyan civil war is significant not just for the bloodshed and instability it will visit on this Mediterranean powder keg. Libya has somewhere between 9.5 tons and 14 tons of mustard gas, according to intelligence sources cited by the Wall Street Journal. As Gadhafi’s regime focuses on holding on to power, as the Libyan military splinters and as the country disintegrates, it’s not difficult to imagine those stockpiles being left unguarded and falling into the hands of America’s enemies. The candidates are numerous: al-Qaida in the Islamic Maghreb; a rogue Libyan faction; Gadhafi’s mercenary army from Chad, Sudan and Niger; a post-Gadhafi regime; or even, if he survives, a post-uprising Gadhafi -- even more paranoid and more unhinged than the man Ronald Reagan once aptly described as “squalid” and “Looney Tunes.”

Any of these scenarios would pose a significant threat to the United States and its closest allies, and making sure none of them transpire must be a priority as events unfold. Trusting the current or future Libyan government -- or governments, in the event of a fracturing of the country -- is simply not an option, which means Washington must contemplate using military force to pre-empt these materials from falling into worse hands.

Toward that end, it’s important to keep in mind that Libya is not Egypt, and the positives and negatives for Washington are significantly different.

On the negative side of the ledger, unlike in Egypt, the U.S. does not have substantive military-to-military contacts or a massive aid spigot in Libya, both of which have been used to great effect in Egypt. Also on the negative side, Gadhafi is no Hosni Mubarak. The latter attempted a limited crackdown against popular protests before stepping aside. The former called in air force and artillery units to murder hundreds, and perhaps thousands, before promising to make the streets run with blood.

On the plus side, Libya does not control a strategic waterway, is not party to a peace agreement that has served as the linchpin of regional stability for 30 years and is not an anchor state in the Arab world. Moreover, Washington does not owe Libya’s leadership anything. There is no need for polite displays of loyalty or diplomatic niceties with this dictator. These realities should give the U.S. more flexibility and freedom of action in dealing with Libya and its chemical weapons material.

If the intelligence on the whereabouts of the chemicals is solid, the U.S. could neutralize or secure the materials quietly and covertly, using CIA and Special Operations units. Nevertheless, inserting U.S. personnel into the middle of a civil war leaves much to be desired. Moreover, moving -- or guarding -- 14 tons of anything is seldom done quietly.

Striking the facilities by air poses less risk to U.S. personnel but still presents challenges. To be sure, the U.S. Air Force is equal to the task. However, a counterproliferation airstrike would probably strip away any plausible deniability. When a complex of buildings 60 miles south of Tripoli goes up in flames in the middle of the night, people are going to know about it, and they will point their fingers at the U.S. Air Force.

Moreover, worries about risk to civilians would have to be taken into account. In this regard, it’s important to remember that a) one of the main ways weaponized mustard is destroyed is by incineration, b) any airstrike would employ ordnance designed to burn off the material, and c) the U.S. bombarded Iraqi facilities during the 1991 Gulf War that produced and stored mustard, anthrax and other agents. Saddam Hussein surely would have told the world if civilians had been harmed by the release of these agents. Even so, it’s up to the White House and the Pentagon to make sure their solution to this problem is not worse than the problem itself.

Yet another possibility is that the U.S. could be compelled to act not on national security grounds but on humanitarian grounds. Backed into a corner, with nothing to lose, Gadhafi could use his mustard stocks against his own people, prompting calls from the international community for intervention -- calls usually answered by the U.S. military.

These sorts of contingency plans may sound scary or unthinkable, but they are surely on the books. We know that the U.S. military has planned counterproliferation strikes against Iran. In the late 1990s, according to reports declassified in 2004, the Clinton administration ordered the Pentagon to develop plans for airstrikes against North Korean nuclear sites. And in the early 1990s, the Gulf War was, in effect, a counterproliferation war. The elder Bush even contemplated military action against Gadhafi’s chemical weapons program.

There are no good options in nightmare scenarios like this. Every option sounds scary because every option is scary. That’s why they are called “nightmares.” The challenge for the White House is to choose the least bad option. And doing nothing is probably no longer a candidate.